Decrease code duplication in ReturnUrlResults.

src/Open.IdentityServer/src/Endpoints/Results/ConsentPageResult.cs

@@ -39,15 +39,8 @@ internal ConsentPageResult(
     public override async Task ExecuteAsync(HttpContext context)
     {
         Init(context);
-        var returnUrl = await BuildReturnUrl(context);
-
         var consentUrl = Options.UserInteraction.ConsentUrl;
-        if (!consentUrl.IsLocalUrl())
-        {
-            // this converts the relative redirect path to an absolute one if we're 
-            // redirecting to a different server
-            returnUrl = context.GetIdentityServerHost().EnsureTrailingSlash() + returnUrl.RemoveLeadingSlash();
-        }
+        var returnUrl = await BuildReturnUrl(context, consentUrl.IsLocalUrl());
 
         var url = consentUrl.AddQueryString(Options.UserInteraction.ConsentReturnUrlParameter, returnUrl);
         context.Response.RedirectToAbsoluteUrl(url);

src/Open.IdentityServer/src/Endpoints/Results/CustomRedirectResult.cs

@@ -55,14 +55,7 @@ internal CustomRedirectResult(
     public override async Task ExecuteAsync(HttpContext context)
     {
         Init(context);
-        var returnUrl = await BuildReturnUrl(context);
-
-        if (!_url.IsLocalUrl())
-        {
-            // this converts the relative redirect path to an absolute one if we're 
-            // redirecting to a different server
-            returnUrl = context.GetIdentityServerHost().EnsureTrailingSlash() + returnUrl.RemoveLeadingSlash();
-        }
+        var returnUrl = await BuildReturnUrl(context, _url.IsLocalUrl());
 
         var url = _url.AddQueryString(Options.UserInteraction.CustomRedirectReturnUrlParameter, returnUrl);
         context.Response.RedirectToAbsoluteUrl(url);

src/Open.IdentityServer/src/Endpoints/Results/LoginPageResult.cs

@@ -39,15 +39,8 @@ internal LoginPageResult(
     public override async Task ExecuteAsync(HttpContext context)
     {
         Init(context);
-        var returnUrl = await BuildReturnUrl(context);
-
         var loginUrl = Options.UserInteraction.LoginUrl;
-        if (!loginUrl.IsLocalUrl())
-        {
-            // this converts the relative redirect path to an absolute one if we're 
-            // redirecting to a different server
-            returnUrl = context.GetIdentityServerHost().EnsureTrailingSlash() + returnUrl.RemoveLeadingSlash();
-        }
+        var returnUrl = await BuildReturnUrl(context, loginUrl.IsLocalUrl());
 
         var url = loginUrl.AddQueryString(Options.UserInteraction.LoginReturnUrlParameter, returnUrl);
         context.Response.RedirectToAbsoluteUrl(url);

src/Open.IdentityServer/src/Endpoints/Results/ReturnUrlResult.cs

@@ -67,8 +67,9 @@ protected void Init(HttpContext context)
     /// Builds a returnUrl using <see cref="IAuthorizationParametersMessageStore"/> if registered, and fallback 
     /// </summary>
     /// <param name="context">The HTTP context.</param>
+    /// <param name="localUrl">Indicates whether the return URL should be local.</param>
     /// <returns>built return url</returns>
-    protected async Task<string> BuildReturnUrl(HttpContext context)
+    protected async Task<string> BuildReturnUrl(HttpContext context, bool localUrl)
     {
         var returnUrl = context.GetIdentityServerBasePath().EnsureTrailingSlash() + Constants.ProtocolRoutePaths.AuthorizeCallback;
         if (AuthorizationParametersMessageStore != null)
@@ -82,6 +83,13 @@ protected async Task<string> BuildReturnUrl(HttpContext context)
             returnUrl = returnUrl.AddQueryString(Request.Raw.ToQueryString());
         }
 
+        if (!localUrl)
+        {
+            // this converts the relative redirect path to an absolute one if we're 
+            // redirecting to a different server
+            returnUrl = context.GetIdentityServerHost().EnsureTrailingSlash() + returnUrl.RemoveLeadingSlash();
+        }
+
         return returnUrl;
     }